Liquefaction-Targeted Ground Motions and Lateral Spreading Driving Stresses

Abstract

Earthquake induced soil liquefaction has been one of the most studied topics in geotechnical engineering over the past 60 years due to its severe impacts on natural and man-made structures. Improving the prediction of liquefaction triggering has already been undertaken for many years, however, in ways that can produce inconsistent, and inaccurate, results in different seismic environments. The first focal point of this thesis is the introduction of a liquefaction-targeted intensity measure that would allow practicing engineers to obtain the benefits of a full probabilistic liquefaction hazard analysis with the same, or less, effort than required by current conventional liquefaction hazard analyses. Lateral spreading is one of the most common, and most severe, effects of liquefaction. Up to three mechanisms are believed to drive lateral spreading. Each of these potential deformation mechanisms is influenced by static shear stresses yet both empirical and semi-empirical procedures for prediction of lateral spreading displacements currently characterize static shear stresses in a crude and incomplete manner. The second focal point of this research was directed toward developing an improved framework for characterizing the initial static shear stresses over a continuous range of site conditions commonly encountered at lateral spreading sites. This framework is intended to lay the foundation for an improved lateral spreading displacement procedure. To accomplish this, numerical analyses were performed to develop a function that can predict the initial static shear stress at depths of lateral spreading interest.